1. Technical Field
The present invention relates to a liquid ejecting head and a liquid ejecting apparatus.
2. Related Art
The liquid ejecting head including a piezoelectric element is known for ejecting the liquid droplet of ink or the like for example, in the liquid ejecting apparatus of an ink jet printer. The liquid ejecting head is provided such that for example, the piezoelectric element deforms a vibration plate according to a driving signal and then pressure within a pressure chamber that is formed lower side of the vibration plate can be changed. Accordingly, the liquid droplet of the ink or the like that is supplied within the pressure chamber can be ejected from the nozzle holes. In the liquid ejecting head, as an object for protecting a piezoelectric material layer of the piezoelectric element that is weak with respect to the destruction for example, by external factors such as moisture or the like, there is a structure in which the piezoelectric material layer is covered by an upper electrode (for example, JP-A-2009-172878 (FIG. 2)).
However, if the piezoelectric element described in JP-A-2009-172878 is driven, since an electric field is applied inside of a boundary of an active region that is defined at an area where the upper electrode and the lower electrode sandwiches and overlaps the piezoelectric material layer, the piezoelectric material layer of the piezoelectric element generates a displacement as the piezoelectric material, and since the electric field is not applied outside thereof, piezoelectric element does not generate the displacement as the piezoelectric material. Thus, there is a problem that concentration of local strain is generated near of boundary of the active region and then crack is easily caused at the piezoelectric material layer.